Why Should We Care about Network Models?

Before we dive into the next video, let's talk about why you should care about the network models we are discussing. If you are a network administrator, you are not necessarily going to be thinking about the OSI Model in your day-to-day work. After all, it is just an abstract idea used to understand networking at a high level. Beyond that, you may not think about it much.

On the other hand, the OSI Model can provide a common language and knowledge base whenever you need to converse with other technical people in your organization. For example, you may need to discuss your network with application programmers and network architects, and having a network model that everyone can relate to can be helpful. If you all know the importance of the Transport Layer and what it represents, you can more easily speak a common language about it. An architect may need to ask a network engineer about what is already existing in the network in order to design a new part of the network. Or an application programmer may need to know how network communications are set up in order to make sure she designs her application in a secure way.

The TCP/IP Model

In the next video, we will introduce the TCP/IP Model, which is another reference model that helps explain how network communications work.

The TCP/IP Model was developed by the Department of Defense developed in the 1960s and is still referenced today. It uses 4 layers to represent some of the same ideas that the OSI Model represents with 7 layers. Some people consider the TCP/IP Model to be more practical, whereas the OSI Model is more abstract.

Take note that we refer to the 4 layers of the TCP/IP Model as the Link Layer, Internet Layer, Transport Layer, and Application Layer, while some people refer to that first layer as the Network Access Layer, rather than the Link Layer. In either case, the idea is the same. That first layer is the one that provides access (or a link) to the network.

Inventory and Security

Another reason why the OSI Model and the TCP/IP Model can be beneficial is because they can help you take an inventory of what you have in your network. You can break your network down and think about it in terms of each layer. What is going on in each layer and have we secured each layer?

We mentioned Defense-in-Depth earlier in the course, and this is one way you can apply it. You can look at your network in an abstract layer-by-layer way and determine whether everything is secure at every level.

One example is if you have an organization where users need to download a lot of sensitive data onto their endpoints, like laptops and smart phones. If they do, then your endpoint security (and security at the Application Layer, for example) might be more important for you than an organization that keeps all its sensitive data in the cloud and does not have users who need to download it.

The OSI Model vs. The TCP/IP Model

Up Next

In the next lesson, we will get familiar with some common ports and protocols. Be sure to answer the questions on the Tasks tab, then click Continue.